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  • Switching jack needed?

    I have a Peavey classic 30 1x12" combo. It does have an external speaker jack. However, I would like to plug in a cab and have the internal speaker shut off. Of course I could wire a jack to the unplugged speaker leads but I don't want to have to re-plug in the internal speaker every time I unplug the cab. I'm pretty sure a switching jack can do this. I just want to verify that this can be done and what type of jack I should get? It would be a mono switching jack right? So jack unplugged would be the internal speaker and jack plugged in would be the cab with NO internal speaker? In addition I could still use the external speaker jack. Anyone have any suggestions?

  • #2
    The internal speaker is 16 ohms, so if you wanted the amp to play into a different speaker, it should also be 16 ohms.

    The simple way would be to mount a jack on a little bracket on the inside wall of the cabinet facing rear. Run the speaker wires to it from the head. The "ground" wire - the blue one - would go to the sleeve of the new jack, then make it continue on to the negative terminal on the internal speaker as before. Now the hot wire - yellow - runs from the head down to the tip contact of the new jack. Then the tip cutout contact is wired to the positive terminal of the internal speaker.

    So now, when the new jack is empty, the output of the amp runs through that cutout contact and on to the speaker, just as always. But if you plug into that jack, not the hot is routed through the tip to the external speaker, and the cutout action disconnects the internal speaker, just as you want. Yes?

    All of this has no effect on the extension speaker jack in the amp. The amp will not have a clue whether it is playing through its internal speaker or through one plugged into your jack.

    It would be possible to mount this jack in the chassis instead of out in the cab, but then you are drilling holes in your amp, plus real estate for a jack on the rear panel is not easy to find. You might wind up having to mount the jack up underneath and back a few inches - not convenient. MY way could be removed leaving only a couple small screw holes in the wood.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Sweet thanks!! There is ample space on the back of the combo to drill a small hole for the jack. However, which type of jack would I need? Here is a list of different jacks from switchcraft:

      http://www.switchcraft.com/Documents...Schematics.pdf

      Could someone find one on that list that would work?

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      • #4
        The schematic in your drawing is III. Like a switchcraft 12A jack.
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


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        • #5
          There is plenty of space on the rear panel, but the problems are inside. There has to be space for the jack between the boards. Have you checked for that? A clear spot on the panel doesn't help you if there is a circuit board right behind it.
          Education is what you're left with after you have forgotten what you have learned.

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          • #6
            Originally posted by Enzo View Post
            There is plenty of space on the rear panel, but the problems are inside. There has to be space for the jack between the boards. Have you checked for that? A clear spot on the panel doesn't help you if there is a circuit board right behind it.
            Sorry. What I meant was there is a piece of wood behind the speaker near the bottom of the amp that could be drilled into. No where near the actual circuitry or reverb tank.

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            • #7
              OH. Sure, you can do that too. My personal preference is for a bracket, as I like to avoid making holes in amps if at all possible. But not everyone feels as I do about that, so down there is as good as anywhere.
              Education is what you're left with after you have forgotten what you have learned.

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